No, that claim is hyperbole. The only Dragon Ball Z characters we know who are faster than light for sure are Birus and Whis. This is like Piccolo Daimao's statement with him destroying the entire world or Kid Boo being universal level which is completely illogical. Besides, if the characters were faster than light by the time of the Freeza Arc, then why didn't Gohan and Company made it in time to Guru's residence before his death? The same applies for Freeza.